COMBINED FILTRATION-SOLID-PHASE EXTRACTION METHOD FOR RECOVERING ORGANIC-SUBSTANCES FROM NATURAL-WATERS IN PREPARATION FOR MUTAGENICITY TESTING

Preparation of water samples for studying toxicological activity requi res that methods for capture and concentration of water-borne chemical s do not chemically alter constituents or add or remove toxicants. In this paper we describe the development of an artifact-free filtration- solid-phase extraction system that recovers particulate organic materi al (POM) and dissolved organic material (DOM) from > 100-L samples of natural waters in preparation for mutagenicity determination and chemi cal characterization. The system consists of 0.45-mu m poly(vinylidene difluoride) membrane filters connected in series to columns packed wi th equal amounts of C-18 and CN bonded-phase sorbents. Extracts of cle aned filters and bonded-phase sorbents were shown to be free of interf erences that are toxic or mutagenic to human B-cells and Salmonella ty phimurium. Likewise, the filtered and sorbed fractions of a 100-L high -purity water sample were neither toxic nor mutagenic to human B-cells or S. typhimurium, demonstrating that the system does not generate bi ologically active artifacts. Recovery studies in which fluoranthene, a n S. typhimurium mutagen, was added to 100-L high-purity water samples yielded > 97% recoveries and showed that the mutagenicity of the samp le was conserved. The average recovery of eight organic compounds adde d as mixtures to 100-L high-purity water samples was 77 +/- 13% (mean +/- SD, n = 2). The POM extract of one of two water samples from the A berjona River (eastern Massachusetts) was found to be mutagenic to hum an B-cells. Benzo[a]pyrene-a potent human B-cell mutagen-was present i n this extract at concentrations sufficient to account for 20-25% of t he observed mutagenicity.